Pinpoint Test B: One Low Beam Headlamp Is Inoperative
Headlamps
Pinpoint Tests
Pinpoint Test B: One Low Beam Headlamp Is Inoperative
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number
Normal Operation
When the Smart Junction Box (SJB) detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the LOW BEAM position, the SJB provides voltage through circuits CLF04 (BN/BU) and CLF05 (BU/GN) to the LH and RH low beam headlamps, respectively. Ground is supplied on circuit GD120 (BK/GN) for the LH headlamp and on circuit GD123 (BK/GY) for RH headlamp.
Vehicles equipped with High Intensity Discharge (HID) headlamps utilize a second (hot at all times) voltage feed to the ballasts from the Battery Junction Box (BJB). Voltage is supplied through circuit SBB13 (GY/RD) for the LH ballast and through circuit SBB16 (VT/RD) for the RH ballast.
When the ballasts receive the headlamp on voltage from the SJB, the ballasts provide high voltage to the HID bulbs.
B2A2E-B2A31:
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Ballast
- HID bulb
- Headlamp assembly (HID-equipped only)
- SJB
PINPOINT TEST B: ONE LOW BEAM HEADLAMP IS INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Due to varying wattage ratings and resulting current draw, certain aftermarket halogen headlamp bulbs may cause the SJB to shut down the short circuit protection, resulting in the low beams becoming inoperative. Verify that the bulbs meet Ford specifications. If the bulbs do not meet Ford specifications, install the correct bulbs. Run the on-demand self-test (required to clear certain DTCs and reset the SJB). Correct any unresolved DTCs. Clear all DTCs. Test the system for normal operation.
NOTE: Make sure the bulb is OK before carrying out diagnostics.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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B1 CHECK FOR SJB SUPPLIED VOLTAGE TO THE HEADLAMP
- Ignition OFF.
- Disconnect: Inoperative Headlamp.
- Place the headlamp switch in the HEADLAMPS ON position.
- For vehicles with halogen headlamps, measure the voltage between the LH headlamp C1284b-1, circuit CLF04 (BN/BU), harness side and ground; or between the RH headlamp C1285b-1, circuit CLF05 (BU/GN), harness side and ground.
- For vehicles with HID headlamps, measure the voltage between the LH headlamp C1284a-3, circuit CLF04 (BN/BU), harness side and ground; or between the RH headlamp C1285a-3, circuit CLF05 (BU/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
For vehicles with halogen headlamps, REPAIR headlamp ground circuit in question for an open. CLEAR the DTCs. REPEAT the self-test.
For vehicles with HID headlamps, GO to B6.
No
VERIFY the SJB fuse 7 (10A) (LH low beam) or fuse 8 (10A) (RH low beam) is OK.
If OK for vehicles with HID headlamps, GO to B2.
If OK for vehicles with halogen headlamps, GO to B3.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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B2 REPEAT THE SJB SELF-TEST AND CHECK FOR VOLTAGE TO THE HEADLAMP
- Place the headlamp switch in the OFF position.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB Self-Test.
- Clear any DTCs and repeat the on-demand self-test.
- Place the headlamp switch in the HEADLAMPS ON position.
- Measure the voltage between the LH headlamp C1284a-3, circuit CLF04 (BN/BU), harness side and ground; or between the RH headlamp C1285a-3, circuit CLF05 (BU/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B5.
No
GO to B3.
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B3 CHECK THE SJB LOW BEAM OUTPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: SJB C2280e.
- For vehicles with halogen headlamps, measure the resistance between the LH headlamp C1284b-1, circuit CLF04 (BN/BU), harness side and ground; or between the RH headlamp C1285b-1, circuit CLF05 (BU/GN), harness side and ground.
- For vehicles with HID headlamps, measure the resistance between the LH headlamp C1284a-3, circuit CLF04 (BN/BU), harness side and ground; or between the RH headlamp C1285a-3, circuit CLF05 (BU/GN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B4.
No
REPAIR circuit CLF04 (BN/BU) (LH headlamp) or circuit CLF05 (BU/GN) (RH headlamp) for a short to ground. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.
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B4 CHECK THE SJB LOW BEAM OUTPUT CIRCUIT FOR AN OPEN
- Measure the resistance between the inoperative headlamp, harness side and the SJB as follows:
- Is the resistance less than 5 ohms?
Yes
GO to B10.
No
REPAIR circuit CLF04 (BN/BU) (LH headlamp) or circuit CLF05 (BU/GN) (RH headlamp) for an open. CLEAR the DTCs. REPEAT the self-test.
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B5 CHECK THE HEADLAMP HARNESS FOR A SHORT
- Inspect the headlamp harness for shorts.
- Is the headlamp harness OK?
Yes
INSTALL a new ballast. REFER to Ballast Service and Repair. TEST the system for normal operation.
No
REPAIR or INSTALL a new headlamp assembly. REFER to Headlamp Assembly Service and Repair. TEST the system for normal operation.
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B6 CHECK FOR HOT AT ALL TIMES VOLTAGE TO THE HEADLAMP
- Place the headlamp switch in the OFF position.
- Measure the voltage between the LH headlamp C1284a-2, circuit SBB13 (GY/RD), harness side and ground; or between the RH headlamp C1285a-2, circuit SBB16 (VT/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B7.
No
VERIFY the BJB fuse 13 (20A) (LH headlamp) or fuse 16 (20A) (RH headlamp) is OK. If OK, REPAIR the circuit in question for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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B7 CHECK THE HEADLAMP GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the LH headlamp C1284a-6, circuit GD120 (BK/GN), harness side and ground; or between the RH headlamp C1285a-6, circuit GD123 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to B8.
No
REPAIR the headlamp ground circuit in question for an open. CLEAR the DTCs. REPEAT the self-test.
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B8 CHECK THE HEADLAMP HARNESS
- Inspect the headlamp harness for opens.
- Is the headlamp harness OK?
Yes
GO to B9.
No
REPAIR or INSTALL a new headlamp assembly. REFER to Headlamp Assembly Service and Repair. TEST the system for normal operation.
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B9 CHECK THE BALLAST
- Substitute a known good ballast and recheck the headlamp operation.
- Does the headlamp operate correctly?
Yes
INSTALL a new ballast. REFER to Ballast Service and Repair. TEST the system for normal operation.
No
INSTALL a new HID bulb. REFER to Headlamp Bulb Service and Repair. TEST the system for normal operation.
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B10 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new SJB. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
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